Because of properties due to its structure and its safeness and harmlessness when released into the environment, Nε-acyl-L-lysine (N-epsilon-acyl-L-lysine) is useful not only as a general cleaning agent in ampholytic detergents, but also in a wide range of industrial fields such as disinfectants, fabric softeners, rust-proofing agents, ore flotation agents, adhesives, clarifying agents, dye fixatives, antistatic agents, emulsifiers, surfactants for cosmetics and the like. In particular, because it dissolves very little in water and common organic solvents and also has water-repellent, antioxidant and lubricating properties, it is being used increasingly in fields such as cosmetics and lubricants as a novel organic powder material (Japanese Patent Application Laid-open (JP-Kokai) No. 61-10503).
Nε-acyl-L-lysine has conventionally been manufactured by dripping an acyl halide into an aqueous alkali solution of an amino acid (Schotten-Baumann method). However, because basic amino acids such as lysine have amino groups in the α-position and ω-position, the principal product of the Schotten-Baumann reaction in this case is a dialkyl basic amino acid, with the ω-acyl basic amino acid being obtained only in small quantities as a by-product. Therefore, for producing co-acyl basic amino acid, a method is known where a basic amino acid is converted to a copper salt of the acyl amino acid and then acylated with an acyl chloride, after which the copper is removed (Yakugaku Zasshi 89, 531 (1969)). These methods involve complex manufacturing steps and operations, use the heavy metal copper, and require large quantities of hydrogen sulfide gas for the copper removal step.
Consequently, there has been a need for development of enzymes that hydrolyze and synthesize Nε-acyl-L-lysine specifically and efficiently under milder conditions, as well as industrial methods for producing the enzymes.
There have previously been few reports of enzymes capable of specifically hydrolyzing Nε-acyl-L-lysines, and while an enzyme from Achromobacter pestifer, one from rat kidneys and one from Pseudomonas sp. KT-83 have been reported, Nε-acyl-L-lysine synthesis reactions using these enzymes have not been reported. Moreover, no enzyme has been discovered that specifically and efficiently acylates the ε-amino group of the two amino groups in lysine.
Regarding synthesis of Nε-acyl-L-lysine using conventional enzymes, it has been reported for example that the capsaicin hydrolyzing and synthesizing enzyme described in JP-Kokai No. 2003-210164 also catalyzes an Nε-acyl-L-lysine synthesis reaction.
As described in JP-Kokai No. 2004-81107, it has been reported that Nε-lauroyl-L-lysine is produced with a yield of 95% by the capsaicin hydrolyzing and synthesizing enzyme described in JP-Kokai No. 2003-210164. However, a long reaction time of two days is required, and because this capsaicin hydrolyzing and synthesizing enzyme exhibits high reactivity on the α-amino group as well as the ε-amino group, a mixture of Nα-lauroyl-L-Lys and Nε-lauroyl-L-Lys was eventually produced.